This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled WASHING MACHINE AND METHOD THEREOF filed with the Korean Industrial Property Office on May 16, 2001 and there duly assigned Serial No. 2001-26668.
1. Field of the Invention
This invention relates, in general, to a washing machine and a method of controlling the same and, more particularly, to a washing machine and a method of controlling the same by interrupting the power of a drive motor before a spin-drying time elapses, thereby stopping a spin-drying tub.
2. Description of the Prior Art
A typical two-tub type washing machine has a washing tub and a spin-drying tub separately set within the housing of the washing machine, with a pulsator provided on the bottom of the washing tub, and a spin-drying motor and a washing motor provided on both sides of the lower portion of the housing for driving the spin-drying tub and the pulsator, respectively. Also, a control panel having a timer for selecting a washing time and a spin-drying time by a user, etc., is provided at one side of the top of the housing.
For such a two-tub type washing machine, when washing time is set by the washing timer after washing water, laundry and detergent are inputted into the washing tub, the pulsator is repeatedly rotated in alternating directions by the washing motor during the washing time so that a washing operation is performed. After completion of the washing operation, the laundry in the washing tub is moved from the washing tub into the spin-drying tub and then the spin-drying time is set by the spin-drying timer, and so the spin-drying tub is rotated at a high speed during the spin-drying time by the spin-drying motor so that a spin-drying operation is performed.
As can be seen from the above description, the two-tub type washing machine is inconvenient in that laundry must be moved from the washing tub to the spin-drying tub after completion of a washing operation and it is problematic in that there is a limitation on a space for installing the washing machine due to the increase of volume of the washing machine by a separation of the spin-drying tub from the washing tub.
In order to solve such inconveniences and problems experienced in the conventional two-tub type washing machine, a one-tub type fully automatic washing machine provided with a spin-drying tub applicable to both washing and spin-drying operations has been proposed. For such a fully automatic washing machine, washing, draining, rinsing, and spin-drying operations are performed automatically when a user inputs laundry into the spin-drying tub and then selects a desired operation course.
However, as such a fully automatic washing machine has to include electrical components, such as a water level sensor and a microcomputer, in order to perform washing, draining, rinsing, and spin-drying operations automatically, there is the problem that the manufacturing cost of the washing machine is increased and it is difficult to maintain or repair the washing machine due to failure of various components.
In view of these shortcomings, a semi-automatic washing machine employing the merits of both the two-tub type washing machine and the fully automatic washing machine has been developed. The semi-automatic washing machine includes a spin-drying tub applicable to both washing and spin-drying operations, and a rotary knob positioned at the top of the housing of the washing machine and allowing a user to select an operation mode of the washing machine as well as a washing time and a spin-drying time.
In such a conventional semi-automatic washing machine, the spin-drying tub is rotatably mounted within an outer tub, with a pulsator installed on the bottom of the spin-drying tub. A drive motor for rotating the spin-drying tub and the pulsator and a power transmission unit for transmitting a driving force of the motor to the spin-drying tub and the pulsator are provided under the outer tub. The power transmission unit is provided with a braking device for braking the spin-drying tub. The braking device brakes or releases the spin-drying tub by pulling or pushing a brake lever connected to a brake band wrapped around the circumferential surface of a brake drum integrated with the spin-drying tub so as to be rotatable along with the tub. In other words, in case of a washing operation, the braking device brakes the spin-drying tub so that the washing operation is performed by the rotation of the pulsator, and in case of a spin-drying operation, the braking device releases the spin-drying tub so that the spin-drying tub is rotated together with the pulsator.
A circuit diagram for a conventional washing machine is shown in FIG. 1. As shown in the drawing, the washing machine consists of a mode selection unit 1 by which a user selects a operation mode (washing, draining, and spin-drying mode) of the washing machine, a washing timer 5 by which a user selects a washing time, and a door switch 2 for supplying or interrupting power in response to an opening or closing of a door. The washing machine also has a spin-drying timer 3 by which a user selects a spin-drying time, a drain motor 4 for controlling a draining operation in conjunction with a braking action of the spin-drying tub, and a motor driving circuit 6 for driving a motor to rotate the spin-drying tub and the pulsator.
The user selects a desired operation mode (washing, draining, and spin-drying mode) by rotating a rotary knob provided on the top of the housing of the washing machine. Switches xe2x80x9cSW1xe2x80x9d and xe2x80x9cSW2xe2x80x9d of the mode selection unit are switched according to an operation mode selected by the user.
If the user selects a washing mode, a first switch xe2x80x9cSW1xe2x80x9d is switched to the xe2x80x9cBxe2x80x9d side, thereby supplying power to the motor driving circuit 6 via the washing timer 5 so that the pulsator is repeatedly rotated in alternating directions by the motor during a washing time set by the washing timer 5. After the washing time selected by the user elapses, the washing timer 5 interrupts power supplied to the motor driving circuit 6.
When a draining mode for draining washing water is set, the first switch xe2x80x9cSW1xe2x80x9d is switched to the xe2x80x9cAxe2x80x9d side and a second switch xe2x80x9cSW2xe2x80x9d is turned off. When the first switch xe2x80x9cSW1xe2x80x9d is switched to the xe2x80x9cAxe2x80x9d side, power is supplied to a solenoid xe2x80x9cSLxe2x80x9d of the drain motor 4 via the door switch 2 and the spin-drying timer 3. The brake lever is pulled by an actuation of the solenoid xe2x80x9cSLxe2x80x9d so that the spin-drying tub is released and a drain port of the outer tub is opened to drain washing water. At this time, as the second switch xe2x80x9cSW2xe2x80x9d remains off, power to the motor driving circuit 6 is interrupted to stop the motor.
When the user selects a spin-drying mode using the mode selection unit 1 and selects a spin-drying time using the spin-drying timer 3, the first switch xe2x80x9cSW1xe2x80x9d is switched to the xe2x80x9cAxe2x80x9d side and the second switch xe2x80x9cSW2xe2x80x9d is switched to a xe2x80x9cCxe2x80x9d side. When the first switch xe2x80x9cSW1xe2x80x9d is switched to the xe2x80x9cAxe2x80x9d side, power is supplied to the solenoid xe2x80x9cSLxe2x80x9d of the drain motor 4 via the door switch 2 and the spin-drying timer 3. When the brake lever is slowly pulled and, after a certain period of time (about 7-10 seconds) elapses, has been completely pulled by an actuation of the solenoid xe2x80x9cSLxe2x80x9d, the brake band is detached from the brake drum by the brake lever so that the spin-drying tub is released and a drain port of the outer tub is opened. With the spin-drying tub released thus, when the second switch xe2x80x9cSW2xe2x80x9d is switched to the xe2x80x9cCxe2x80x9d side, power is supplied to a starting switch xe2x80x9cSW3xe2x80x9d which in turn supplies power to the motor driving circuit 6 after a certain period of time (7-10 seconds) elapses. Accordingly, the spin-drying tub and the pulsator are rotated at a high speed by the motor. After this, when the spin-drying time selected by the user is passed, as the spin-drying timer 3 interrupts power supplied to the solenoid xe2x80x9cSLxe2x80x9d, the brake lever is unrestricted so that the brake band comes into contact with the brake drum to brake the spin-drying tub.
With such a conventional washing machine, as the spin-drying tub rotating at a high speed by the motor is suddenly braked by the contact of the brake band with the brake drum when spin-drying time has elapsed, the problems are present that lifetime of the braking device becomes short due to an accelerated abrasion of the brake band, in addition to increased vibration and noise occurring at the time of braking of the spin-drying tub.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a washing machine and a method of controlling the same, which are capable of lengthening the lifetime of a braking device and reducing vibration and noise occurring at the time of braking of the spin-drying tub by interrupting the power to a motor before spin-drying time has elapsed.
In order to accomplish the above object, according to an aspect of the present invention, a washing machine selected in its operation mode and operation time by a user, comprises a spin-drying tub provided in an outer tub for performing both washing and spin-drying operations; a motor for rotating the spin-drying tub; a braking means for braking the spin-drying tub; a mode selection means for selecting a spin-drying mode; and a spin-drying timer for interrupting power to the motor before the spin-drying tub is braked in the spin-drying mode so that the spin-drying tub continues to rotate by its own inertia.
According to another aspect of the present invention, a method of controlling a washing machine selected in its operation mode and operation time by a user, comprises the steps of selecting a spin-drying mode and a spin-drying time; rotating a spin-drying tub by supplying power to a motor in the spin-drying mode; interrupting power to the motor before the selected spin-drying time has elapsed so that the spin-drying tub is rotated by its own inertia; and braking the spin-drying tub after the selected spin-drying time has elapsed.